1. Field of the Invention
The present invention relates to a method and apparatus for controlling a gear-shift of a motor-driven gear shifter in which the gear-shift is electrically performed by a motor. In particular, the present invention relates to a method and an apparatus for detecting a rotational position of a shift drum, when the shift operation is not normally ended and thereby the shift drum is in the half-neutral state, which automatically executes the shift operation.
2. Description of Related Art
A motor-driven gear shifter in which gear-shift is electrically performed by response to a shift-up or shift-down operation has been disclosed in Japanese Patent Laid-open No. Hei 5-39865. Further, a motor-driven gear shifter in which not only the shift operation but also the clutch connection/disconnection is performed by a motor has been disclosed by the present applicant in Japanese Patent Laid-open No. Hei 11-82709.
In the above-described motor-driven gear shifters, when the motor is driven to a desired shift direction, a shift drum is intermittently turned via a ratchet mechanism, and a shift fork engaged with the shift drum is translated up to a specific position in the parallel direction. A sleeve is engaged with a tip of the shift fork. The sleeve is translated along with the translation of the shift fork, to be meshed with a gear corresponding to a desired gear-shift stage, thereby transmitting a drive force of an engine to a drive wheel at a specific reduction ratio.
In the above-described motor-driven gear shifter, however, there may occur a pseudo neutral state (referred to sometime as xe2x80x9chalf neutral statexe2x80x9d) in which even if the shift drum is turned to a normal intermittent angle and the sleeve moved by the shift fork is temporarily meshed with the gear, the sleeve having been once meshed with the gear is released therefrom depending on a difference in rotation and a difference in phase upon meshing operation between the sleeve and the gear, thereby failing to transmit the drive force of the engine to the drive wheel.
In such a case, for a conventional semi-automatic motor-driven gear shifter in which a shift operation is required to be performed upon a gear-shift, it is required to release the shift drum from the half neutral state by repeating the shift operation by a driver who has found the half neutral state.
On the contrary, for a full-automatic motor-driven gear shifter in which gear-shift is automatically performed with a vehicle speed and a throttle opening degree taken as parameters, since the gear-shift operation cannot be repeated by the driver""s intention even if the shift drum has been in the half neutral state, with a result that the shift drum cannot be quickly released from the half neutral state.
An object of the present invention is to solve the above-described prior art technical problem, and to provide a method and an apparatus for controlling a gear-shift of a motor-driven gear shifter, which are capable of detecting, when the shift operation is not normally ended and thereby a shift drum is in the half neutral state, which automatically executes the shift operation again.
To achieve the above object, the present invention provides a method and an apparatus for controlling gear-shift of a motor-driven gear shifter in which a motor is driven in a desired shift direction, to intermittently turn a shift drum, thereby shifting one gear stage to another gear stage.
The above-described method is characterized in that the rotational position of the shift drum is monitored, and when the shift drum stays at a rotational position other than a rotational position corresponding to a desired gear stage.
The above-described apparatus is characterized by including detecting means for detecting the rotational position of the shift drum; and retry-shift means for re-driving, when the shift drum stays at a rotational position other than a normal rotational position, the motor in the shift direction.
With this configuration, it is electrically detected whether or not the shift drum is at the half neutral position, and if the shift drum is at the half neutral position, retry-shift operation is automatically performed.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.